Need help regarding the employment contract breaking

I had signed an employment contract with my company in Chennai when I joined 7 months back. I was recruited through a pre-placement Interview as I had interned in the same company during summers. After I did my MBA, I joined this company after a small Skype interview. I was promised(verbally) that I would be given a particular product management role and that was the sole reason I accepted the offer even though the package was low and there was a 2 year bond. After I joined the company, I was given some other product to manage and was not in my area of interest. I spoke to my manager about it, but to no avail. Later, I found out that I was offered a discriminatory package compare to similar trainees who joined with me. Now, I have put the papers and the company is asking for 4 Lakh rupees as charges for breaking bond. I was not given any specialized training in written, but I had visited our factory at times to see the product and process of manufacturing. Other training was common training for all employees. What can I do to negotiate the bond breaking charge ?